Lesson 32 Limits and Tolerances 机械工程专业英语 教学课件
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interchangeable. 制造机器零件应使它们具有互换性。
In other words, each part of a machine or mechanism is made to a certain size and shape so it will fit into any other machine or mechanis of the same type. 换句话说，每一个机器或机构的零件应制造成具有 一定的尺寸和形状以便使之能装入到任何其他同类 型的机器或机构中。
These are known as the limits.The difference between upper and lower limits is called the tolerance. 这两个尺寸被称为极限尺寸。最大和最小极限尺寸 之间的差值就称做公差。
A tolerance is the total permissible variation in the size of a part.
预备知识
机械工程专业英语
Lesson 32 Limits and Tolerances 一、预备知识 The primary purposes of jigs and fixtures is to: Reduce the cost of production Maintain consistent quality Maximize efficiency Enable a variety of parts to be made to correct specifications
The amount of this variation depends on the kind of part being manufactured.
偏差的大小取决于要制造零件的种类。
课文分析
机Fra Baidu bibliotek工程专业英语
Lesson 32 Limits and Tolerances
For example, a part might be made 6 in. long with a variation allowed of 0.0003 (threethousandths)in. above and below this size. 例如，一个零件6英寸长，其长度偏差为±0.003英 寸(即正负千分之三英寸)。
English for Mechanical Engineering
机械工程专业英语
常州工学院机电工程学院
徐红丽
机械工程专业英语
Lesson 32 Limits and Tolerances
一、预备知识 Fixture
A fixture is a workholding or support device used in the manufacturing industry. What makes a fixture unique is that each on is built to fit a particular part or shape. The main purpose of a fixture is to locate and in some cases hold a workpiece during either a machining operation or some other industrial process. A jig differs from a fixture in that it guides the tool to its correct position in addition to locating and supporting the workpiece.
预备知识
机械工程专业英语
Lesson 32 Limits and Tolerances
二、词汇 interchangeable 可互换的
tolerance 公差
词汇
机械工程专业英语
Lesson 32 Limits and Tolerances
三、课文分析 Machine parts are manufactured so they are
公差是一个零件尺寸允许的总的变化范围。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
The basic size is that size from which limits of size are derived by the application of allowances and tolerances. 基本尺寸是从该尺寸出发，运用偏差和公差推导出 极限尺寸所依据的尺寸．
It is not only impossible, but also impractical to make many parts to an exact size.
把许多零件制造成精确的尺寸，那不仅是不可能的，
而且也是不实际的。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
This is because machines are not perfect, and the tools become worn.A slight variation form the exact size is always allowed. 这是因为机床总是存在误差的，刀具也会逐渐磨损 的，相对精确尺寸稍有点偏差也是允许的。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
To make the part interchangeable, each individual part must be made to a size that will fit the mating part in the correct way. 为了使零件具有互换性，每个零件都必须把它制造 成一定尺寸以便将以合适的方式装入到与其相配合 的零件中去．
Therefore, the part could be 5.997 to 6.003 in. and still be the correct size. 因此该零件可以是5.997到6.003英寸长，而仍然是 合格的尺寸。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
In other words, each part of a machine or mechanism is made to a certain size and shape so it will fit into any other machine or mechanis of the same type. 换句话说，每一个机器或机构的零件应制造成具有 一定的尺寸和形状以便使之能装入到任何其他同类 型的机器或机构中。
These are known as the limits.The difference between upper and lower limits is called the tolerance. 这两个尺寸被称为极限尺寸。最大和最小极限尺寸 之间的差值就称做公差。
A tolerance is the total permissible variation in the size of a part.
预备知识
机械工程专业英语
Lesson 32 Limits and Tolerances 一、预备知识 The primary purposes of jigs and fixtures is to: Reduce the cost of production Maintain consistent quality Maximize efficiency Enable a variety of parts to be made to correct specifications
The amount of this variation depends on the kind of part being manufactured.
偏差的大小取决于要制造零件的种类。
课文分析
机Fra Baidu bibliotek工程专业英语
Lesson 32 Limits and Tolerances
For example, a part might be made 6 in. long with a variation allowed of 0.0003 (threethousandths)in. above and below this size. 例如，一个零件6英寸长，其长度偏差为±0.003英 寸(即正负千分之三英寸)。
English for Mechanical Engineering
机械工程专业英语
常州工学院机电工程学院
徐红丽
机械工程专业英语
Lesson 32 Limits and Tolerances
一、预备知识 Fixture
A fixture is a workholding or support device used in the manufacturing industry. What makes a fixture unique is that each on is built to fit a particular part or shape. The main purpose of a fixture is to locate and in some cases hold a workpiece during either a machining operation or some other industrial process. A jig differs from a fixture in that it guides the tool to its correct position in addition to locating and supporting the workpiece.
预备知识
机械工程专业英语
Lesson 32 Limits and Tolerances
二、词汇 interchangeable 可互换的
tolerance 公差
词汇
机械工程专业英语
Lesson 32 Limits and Tolerances
三、课文分析 Machine parts are manufactured so they are
公差是一个零件尺寸允许的总的变化范围。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
The basic size is that size from which limits of size are derived by the application of allowances and tolerances. 基本尺寸是从该尺寸出发，运用偏差和公差推导出 极限尺寸所依据的尺寸．
It is not only impossible, but also impractical to make many parts to an exact size.
把许多零件制造成精确的尺寸，那不仅是不可能的，
而且也是不实际的。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
This is because machines are not perfect, and the tools become worn.A slight variation form the exact size is always allowed. 这是因为机床总是存在误差的，刀具也会逐渐磨损 的，相对精确尺寸稍有点偏差也是允许的。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances
To make the part interchangeable, each individual part must be made to a size that will fit the mating part in the correct way. 为了使零件具有互换性，每个零件都必须把它制造 成一定尺寸以便将以合适的方式装入到与其相配合 的零件中去．
Therefore, the part could be 5.997 to 6.003 in. and still be the correct size. 因此该零件可以是5.997到6.003英寸长，而仍然是 合格的尺寸。
课文分析
机械工程专业英语
Lesson 32 Limits and Tolerances